1. Field of the Invention
The invention relates to a monitoring apparatus, more particularly to a monitoring apparatus for wheel units of an automobile.
2. Description of the Related Art
Referring to FIG. 1, a conventional brake assembly for braking a brake disk of a wheel is shown to include a pad-mounting seat unit 76, a brake pad unit 78, a retaining housing 90, a compression spring 94, a sound generating unit 88, and a seal 95.
As illustrated, the brake pad unit 78 is fixed on the pad-mounting seat unit 76, and has a retention recess 80. The brake pad unit 78 is movable together with the pad-mounting seat unit 76 toward the brake disk (not shown) to frictionally contact the brake disk and stop rotation of the wheel. The housing 90 is fixed on the pad-mounting seat unit 76, and defines a chamber 106 with a distal open end 92. The sound generating unit 88 includes a block body 85 disposed slidably and movably within the chamber 106, and having a fastener element 84 with a bifurcated enlarged end 86 that extends into the recess 80 of the brake pad unit 78 via a passage 82 in the brake pad unit 78 so as to be retained in the recess 80. The seal 95 is removably mounted on the open end 92 of the housing 90 so as to conceal the sound generating unit 88. The compression spring 94 is disposed in the chamber 106, and has two opposite ends abutting against the brake pad unit 78 and the sound generating unit 88.
In case the enlarged end 86 of the fastener element 84 wears out concurrently with the brake pad unit 78 due to frequent braking operation of the brake assembly, the block body 85 will be pushed away from the brake pad unit 78 by virtue of the restoration force of the compression spring 94 so as to remove the seal 92 from the housing 90. Under this condition, air flows into air passages 102, 104 in the block body 85 to activate a diaphragm 100 that is disposed within the block body 85 of the sound generating unit 88, thereby generating a warning sound.
The aforesaid conventional brake assembly includes a relatively large number of components, each of which is formed separately prior to assembly thereof, thereby resulting in a long assembly time and high manufacturing costs.
Therefore, the object of the present invention is to provide a monitoring apparatus for wheel units of an automobile that can monitor pressure condition in pneumatic tires of the wheel units and wear condition of brake pads of the wheel units.
According to the present invention, a monitoring apparatus is adapted for use with a wheel unit of an automobile. The wheel unit includes a pneumatic tire and a brake system for braking the pneumatic tire. The brake system includes a conductive first brake member mounted on the pneumatic tire, and a second brake member provided with a brake pad that is disposed adjacent to the first brake member. The brake system is operable so as to enable the second brake member to move toward the first brake member such that the brake pad frictionally contacts the first brake member to brake the pneumatic tire. The monitoring apparatus comprises:
a conductive coupling member adapted to be embedded in the brake pad such that the conductive coupling member is spaced apart from the first brake member by a thickness of the brake pad when wearing of the brake pad has yet to reach a predetermined worn-out state;
a wear detecting circuit coupled electrically to the coupling member for detecting wear condition of the brake pad, the wear detecting circuit being capable of outputting a wear signal when the brake system is activated and the brake pad ceases to space apart the conductive coupling member from the first brake member;
a pressure detecting unit for detecting pressure condition in the pneumatic tire and for generating a pressure signal in accordance with the pressure condition in the pneumatic tire;
a processing unit coupled electrically to the wear detecting circuit and the pressure detecting unit for receiving the wear signal and the pressure signal therefrom; and
an indicating unit coupled electrically to and enabled by the processing unit to indicate whether the brake pad has reached the predetermined worn-out state and to further indicate the pressure condition in the pneumatic tire.